Various side knock-type mechanical pencils have been proposed. One example of a conventional side knock-type mechanical pencil is disclosed in U.S. Pat. No. 3,883,253 and is illustrated in FIG. 1. According to this prior art example, a knock lever 22 is mounted within a side hole 21 in a cylindrical shell 20 which houses a chuck mechanism, and a piece of lead is pushed out of the pencil by pressing ("knocking") the knock lever 22 with a finger tip while grasping the pencil in the vicinity of the knock lever. More particularly, upon operation of the knock lever 22, an actuating portion 22a thereof comes into abutment with a slanted portion 24a of a slider 24 provided on the elongated cylindrical portion 27 of chuck 26, which elongated cylindrical portion is connected to a lead tank 23. This causes the lead tank 23 to move forward inside the cylindrical shell 20 against a backward biasing force of a spring 25, whereby the chuck 26 opens slightly and permits delivery of a piece of lead.
In such a conventional mechanical pencil, the side knock mechanism is generally positioned in the grip portion of the shell 20. Therefore, in the case where a grip member formed of an elastic material such as rubber is formed in that portion, the diameter of the grip portion becomes large, so the diameter of the lead tank 23 is sized to permit one lead piece to pass therethrough, and a space for spare leads is formed in the rear portion of the shell 20.
Recently, however, there has been proposed a mechanical pencil having in the rear portion thereof a mechanism for the delivery of a rod-like article such as an eraser or the like. In a side knock-type mechanical pencil having such a mechanism incorporated therein, there is no space for spare leads in the rear portion thereof. In addition, the diameter of the lead tank 23 is required to be made small, and thus it has been difficult to accommodate spare leads.